Re: [PATCH 1/2] drm/i915: fold wait_for_atomic_us into wait_for_atomic

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 28, 2013 at 12:03:24AM +0100, Daniel Vetter wrote:
> Since
> 
> commit bcf9dcc1e6269fac674e41f25d007ff75f76e840
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Sun Jul 15 09:42:38 2012 +0100
> 
>     drm/i915: Workaround hang with BSD and forcewake on SandyBridge
> 
> and
> 
> commit 0cc2764cc4a4bd73df55f8893c871778cf7ddd0f
> Author: Ben Widawsky <ben@bwidawsk.net>
> Date:   Sat Sep 1 22:59:48 2012 -0700
> 
>     drm/i915: use cpu_relax() in wait_for_atomic
> 
> these two macros are essentially the same, so unify them. We keep the
> _us version since it's a nice documentation for smaller timeouts.
> 
> Cc: Jack Winter <jbh@alchemy.lu>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_drv.h | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 54bc2ea..c8c1979 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -50,21 +50,10 @@
>  	ret__;								\
>  })
>  
> -#define wait_for_atomic_us(COND, US) ({ \
> -	unsigned long timeout__ = jiffies + usecs_to_jiffies(US);	\
> -	int ret__ = 0;							\
> -	while (!(COND)) {						\
> -		if (time_after(jiffies, timeout__)) {			\
> -			ret__ = -ETIMEDOUT;				\
> -			break;						\
> -		}							\
> -		cpu_relax();						\
> -	}								\
> -	ret__;								\
> -})
> -
>  #define wait_for(COND, MS) _wait_for(COND, MS, 1)
>  #define wait_for_atomic(COND, MS) _wait_for(COND, MS, 0)
> +#define wait_for_atomic_us(COND, US) _wait_for((COND), \
> +					       usecs_to_jiffies((US)), 0)

usecs_to_jiffies() is wrong here. DIV_ROUND_UP((US), 1000) maybe,
or change _wait_for() to take the timeout in jiffies.

>  
>  #define KHz(x) (1000*x)
>  #define MHz(x) KHz(1000*x)
> -- 
> 1.7.11.7
> 
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-- 
Ville Syrjälä
Intel OTC